Heat transfer fluid conduit wrapping for vessels



May 9, 1967 B. VIHL 3,31

HEAT TRANSFER FLUID CONDUIT WRAPPING FOR VESSELS Filed April 13, 1966 9Sheets-Sheet l FIGQI FIG.2

INVENTOR.

BERNHARD VIHL ATT RNEYS B. vn-u. 3,318,376

HEAT TRANSFER FLUID CONDUIT WRAPPING FOR VESSELS May 9, 1967 9Sheets-Sheet 2 Filed April 13, 1966 F|G.3v

INVENTOR.

BERNHARD VIHL TTORNEY B. VIHL May 9, 1967 3,318,376

HEAT TRANSFER FLUID counum WRAPPING FOR VESSELS Filed April 13, 1966 9Sheets-Sheet 3 INVENTOR. BERNHARD VIHL %?m %L AT ORNEYS May 9, 1967 B.V'IHL I HEAT TRANSFER FLUID CONDUIT WRAPPING FOR VESSELS Filed April 13,1966 9 Sheets-Sheet 4 Fl .IO

I INVENTOR. BERNHARD VIHL TORNEY ViHL May 9, 1967 HEAT TRANSFER FLUIDCONDUIT WRAPPING FOR VESSELS Filed April 13, 1966 9 Sheets-Sheet 5INVENTOR.

R. A m W W R m E T 7A May 9, 1967 Filed April 13, 1966 FIG. l5

B. vu-n. 3,318,376

HEAT TRANSFER FLUID CONDUIT WRAPPING FOR VESSELS 9 Sheets Shee'c 6 AORNEYS y 9, 1967 B. VIHL Q 3,318,376

HEAT TRANSFER FLUID CONDUIT WRAPPING FOR VESSELS Filed April 15, 1966 9Sheets-Sheet 7 FIGJB 19% F l6. I6

IN VENTOR BERNHARD VIHL ATTORNEYS B. ViHL.

May 9, 1967 HEAT TRANSFER FLUID CONDUIT WRAPPING FOR VESSELS Filed April15, 1966 9 Sheets-Sheet 8 ON QE INVENTOR. BERNHARD VIHL TTORNEYS y 9,1967 B. VIHL. 3,318,376

HEAT TRANSFER FLUID CONDUIT WRAPPING FOR VESSELS Filed April 13, 1966 9Sheets-Sheet 9 I N VEN TOR. Bag/#19190 V/HL BY ;?42 W ,qrrowers UnitedStates Patent 3,318,376 HEAT TRANSFER FLUED CONDUIT WRAPPING FOR VESSELSBernhard Vihl, 2 Glenwood St, Clifton, NJ. 07013 Filed Apr. 13, 1966,Ser. No. 559,699 30 Claims. (Cl. 165-469) This application is acontinuation-in-part of application Ser. No. 453,561 filed in the UnitedStates Patent Office on Apr. 29, 1965, now abandoned, which in turn is acontinuation-in-part of application Ser. No. 362,725 filed in the UnitedStates Patent Office on Apr. 27, 1964, now abandoned.

The present invention relates to heat transfer fluid conduit wrappingfor vessels. It further relates to such conduit wrapping which maycontain fluids under high pressure and be attached or affixed to avessel for heat transfer, and it further relates to such conduitwrapping which may be affixed to a vessel for purposes of rapidlyalternated heating and cooling of one or more zones, depending on theheating or cooling needs.

It is an object of the present invention to provide a heat transferfluid conduit wrapping in the general form of a trough having outwardlycurved flaring edges along its open side, this trough being preferablyof a generally rounded cross sectional configuration.

It is another object of the present invention to provide a heat transferfluid conduit wrapping which, with its longitudinal edges securelyfastened or attached in fluidtight relation to the surface of a vesselas by welding, is transversely configured to flex without unduestressing through fairly rapid and extensive changes of temperature orpressure.

It is another object of the present invention to provide a vessel havinga heat transfer fluid conduit wrapping of the kind described withadjacent turns of the wrapping welded along their longitudinal edgesboth to the surface of the vessel and to each other, the wrapping beingafiixed to either the exterior or the interior surface of the vessel.

It is another object of the present invention to provide a vessel havinga heat transfer fluid conduit wrapping of the kind described withadjacent turns of the wrapping welded along their longitudinal edgesboth to the surface of the vessel and to each other, the vessel itselfbeing of either cylindrical or another shape, including an angularshape.

It is another object of the present invention to provide a vessel havinga heat transfer fluid conduit wrapping of the kind described which, aswrapped, may contain fluids under high pressure while beingsubstantially lighter than a vessel of the same capacity provided withheat transfer fluid jacketing of the traditional kind.

It is another object of the present invention to provide a vessel havinga plurality of heat transfer fluid conduit wrappings of the kinddescribed affixed to it in spaced, non-interwrapped array to permitselective zone heat transfer to or from the vessel.

It is another object of the present invention to provide a vessel havinga plurality of heat transfer fluid conduit wrappings of the kinddescribed affixed to it in interwrapped array to permit rapid changes ofheat transfer conditions, for example, rapidly alternated conditions ofheating and cooling, to be effected with respect to a given selectedzone of the vessel.

It is another object of the present invention to provide a vessel havinga plurality of heat transfer fluid conduit wrappings of the kinddescribed affixed to it in superimposed array to permit rapid changes ofheat transfer conditions, for example, rapidly alternated conditions ofheating and cooling, to be effected with respect to a given selectedzone of the vessel.

Patented May 9, 1967 These and other objects and advantages of thepresent invention as well as its nature and substance will be moreclearly perceived and fully understood by referring to the followingdescription and claims taken in connection with the accompanyingdrawings in which:

FIG. 1 represents a view in side elevation of a hemisperically bottomedvessel provided with heat transfer fluid conduit wrapping according tothe present invention on both its side and bottom exterior surfaces,that on the side exterior surface being in two segments for selectivezone heat transfer, and that on the bottom exterior surface beingseparate from that on the side surface for further selectivity;

FIG. 2 represents a bottom plan view of the vessel of FIG. 1;

FIG. 3 represents an enlarged fragmentary view in sectional elevation ofthe vessel of FIGS. 1 and 2 taken along line 3-3 in FIG. 2 looking inthe direction of the arrows;

FIG. 4 represents an enlarged plan view of the bottom volute transitionpiece of the heat transfer fluid conduit wrapping shown in FIGS. 1 and2;

FIG. 5 represents a view in side elevation of the transition piece ofFIG. 4 taken along line 5-5 in FIG. 4 looking in the direction of thearrows;

FIG. 6 represents a transverse sectional view of the transition piece ofFIG. 4 taken along line 6-6 in FIG. 4 looking in the direction of thearrows;

FIG. 7 represents a transverse sectional view of a fragment of thetransition piece of FIG. 4 taken along line 77 in FIG. 4 looking in thedirection of the arrows;

FIG. -8 represents a fragmentary side view, partly in section, of thevessel of FIGS. 1 and 2 particularly showing an alternate :bottom outletconstruction;

FIG. 9 represents a fragmentary perspective view of a segment of heattransfer fluid conduit wrapping according to a preferred embodiment ofthe present invention;

FIG. 10 represents a sectional view of a vessel wall fragment with heattransfer fluid conduit wrapping upon it according to the presentinvention before actual attachment of the wrapping to the wall bywelding;

FIG. 11 represents an enlarged view of a portion of FIG. 10 afterattachment of the wrapping to the wall particularly showing a deposit ofweld material whereby adjacent turns of wrapping are fastened to thevessel wall and also to each other;

FIG. 12 represents a fragmentary view in side elevation of adrum-bottomed vessel provided with helically-andspirally-wound transferfluid conduit wrappings on its exterior surface according to the presentinvention with two segments of wrapping being interwrapped on each of aplurality of zones of the vessel wall;

FIG. 13 represents a fragmentary View in sectional elevation through thevessel of FIG. 12 taken on a diametral plane with the direction of viewin FIG. 13 being the same as that in FIG. 12;

FIG. 14 represents a fragmentary view in sectional elevation of a vesselprovided with heat transfer fluid conduit wrapping on its exteriorsurface according to the present invention with a first segment ofwrapping aflixed directly to the vessel Wall and a second segmentsuperimposed on the first segment;

FIG. 15 represents a fragmentary view in sectional elevation of a vesselprovided with heat transfer fluid conduit wrapping on its exteriorsurface according to the present invention with a first segment ofwrapping aflixed directly to the vessel wall, a second segmentsuperimposed on the first segment, and a third segment superimposed onthe second segment;

FIG. 16 represents a fragmentary view in sectional elevation taken alongline 1616 in FIG. 17, looking in the direction of the arrows, of acylindrical, drum- 'of vessel 22 according to FIGS. 1-3.

4-7 the transition piece is represented as it might be made duit definedwithin this wrapping is provided for theat-- tachment of a pipeconductor;

FIG. 19 represents an end view of the closing means shown in FIG. 18taken along line 19-19 therein looking in the direction of the arrows;

FIG. 20 represents a fragmentary view in sectional elevation taken alongline 20--20 in FIG. 21, looking in the direction of the arrows, of arectangular, flat-bottomed vessel having heat transfer fluid conduitwrappings affixed to its'side and bottom interior surfaces;

FIG. 21 represents a sectional plan view of the vessel of FIG. 20 takenalong line 2121 therein looking in the direction of the arrows;

FIG. 22 represents a perspective view of a return bend heat transferconduit wrapping according to thepresent invention before it is attachedto a vessel; and

FIG. 23 represents a perspective view of a vessel to which return bendheat transfer conduit wrappings of the type illustrated in FIG. 22 andother heat transfer conduit wrappings according to the present inventionare attached.

Referring now to the drawings in detail, especially FIGS. 1-7 thereof,20 designates the overall assembly of a vessel such as a chemicalblending retort provided with helically and spirally wound heat transferfluid conduit wrappings according to the present invention. The vesselitself is designated 22, and is characterized by a drum-shaped head anda hemispherically-shaped bottom. Between its top and bottom ends it isof essentially straight cylindrical configuration. The top of the vesselis provided with various fittings to serve as connections for influentfluids, pressure gauges, thermometers, stirring devices, etc. Thesefittings, which are shown for purposes of example only, do not bythemselves constitute any part of the present invention. At its lowerend, vessel 22 is provided with a bottom outlet fitting 23 which isdiscussed in'sorne detail hereinafter in connection'with a form of thepresent invention slightly alternate from that shown in FIGS. l-7.

Aflixed fluid-tightly to the exterior surface of the central cylindricalwall portion of vessel 22 are two helically Wound heat transfer fluidconduit wrappings 24 and 26. A third wrapping 28 of mixed helical andspiral configuration which terminates in a primary spirally wound volutetransition piece 30 at its lower end. is atfixed to the exterior surfaceof the vessels hemispherical bottom. Assuming that these wrappingsdefine conduits through which a condensableheating fluid, for example,steam, is to be carried, the inlet connection of each conduit so definedwould be at the conduits upper end and the outlet connection at itslower end so that any liquid water formed through the condensation ofsteam would be easily drained away. Accordingly, wrapping segment 24 ispro- 'vided with inlet. fitting 32 and outlet fitting 34; Wrappingsegment 26 is provided with inlet fitting 36 and outlet fitting 38, andwrappingsegment 28 is provided with inlet fitting and outlet fitting 42.

Volute transition piece 30 as shown in FIGS. '4-7 is not completelyshaped to fit the hemispherical bottom Rather in FIGS.

as a standard trough-like piece having its open side spirallywound in asingle plane and being amenable to further shaping to suit therequirements of 'a particular installation. As is shown in FIGS. 4 and7, transition and the wrappings aflixed to it due to changes in tempiece30 has an arcuate length of about 270 and a transverse cross sectionalarea which enlarges continuously from the end having outlet fitting 42to the end which is joined to wrapping segment 28. The enlargement ofthe cross sectional configuration facilitates the draining to outletfitting 42 of any liquid in Wrapping segment 28 or transition piece 30,for example, water formed by condensation of steam upon the walls oftransistion piece 30 or any of the wrapping segments such as wrappingsegment 28 located on the vessel above transition piece 30 and feedinginto it. The larger of the two ends of transition piece 30' is connectedto wrapping segment 28 in a fluid-tight manner, preferably by welding,and its outwardly curved flaring edge portions are connected to thesurface of vessel 20, also preferably by welding. In affixing it to avessel, transition piece 30 is shaped to correspond to the shape of thevessel surface to which it is attached, which in the embodiment shown inFIG. 3, is substantially hemispherical.

It is to be noted that wrapping segments 24, 25- and 28 are arrangedserially along the surface of vessel 22 from top to bottom. Thus, ifsteam be supplied to the conduit defined by wrapping segment 24 alone,only a particularly selected zone of the vessel will be heated. Bysupplying steam to only one or some of the conduits defined by theseveral wrappings, therefore, selective zone control of heat applied tothe vessel may be achieved. Whether one, some, or all of the conduitsdefined by the Wrappings of this invention are supplied with steam orsome other heating fluid will, of course, depend upon the amount ofheating or nature of the reaction desired to be carried out within thevessel 22.

Although for purposes of example and description it has been assumedthat steam is to be used in the conduits defined by wrapping segments24, 26 and 28, it will be apparent. to those skilled in the art thatthese conduits may just as well be used to carry heating fluids otherthan steam, for example, hot Water. Similarly, if the effect desiredwithin the vessel 22 be one of cooling rather than heating, the conduitsdefined by the wrappings afl'ixed to the vessels exterior wall surfacesmay carry cold water or some other refrigerant with a selectively ofzone heat transfer or temperature control which is as flexible as thataforedescribed in the case of heating steam. Further, where either anon-condensing or a non-vaporizing fluid is to be circulated through theconduits, whether this fluid be one for heating or for cooling of thevessels contents, it may be circulated upwardly through thewrapping-defined conduits rather than downwardly through them, ifdesired. In this circumstance, fittings 34, 38, and 42 would becomeinlet fittings, and fittings 32, 36, and 40 would become outletfittings. An insulated material appropriate for heat or cold as requiredwill be applied to the overall assembly 20 of the vessel and itswrappings.

The preferred mode of attachment or aifixation of wrappings .24, 26, and28 to the exterior wall surfaces of vessel 22 is by welding, and it is afeature of the present invention that adjacent wrapping turns are woundonto the vessel surfaces sufficiently close to each other that a singledeposit of weld material will be effective to fasten adjacent turns bothto the vessel wall and to each other. This provides an economy ofwelding with respect to both material deposited and time required forthe overall operation of attaching the wrapping segments.

This mode of attachment of wrapping segments to vessel wall surfaceswill be particularly appreciated upon consideration of FIG. 3. In thisfigure, it may be seen that the successive turns of heat transfer fluidconduit wrapping in any particular segment of this wrapping are arrayedin a more or less bellows-like formation. Thus, when there aredimensional changes in vessel 22 perature, even fairly wide and rapidtemperature changes,

these wrappings can flex transversely as Well as tQI- 'sionally in aspring-like or bellows-like manner Without the setting up in them of anyparticularly high stresses which might serve to fracture the wrappingsor break them loose from their joints to each other or to the vesselwall.

It will be seen further upon consideration of FIG. 3 that there are nocontinuous areas of either vessel wall surface or heat transfer fluidconduit wrapping surface having relatively large dimensions of bothlength and breadth which can be exposed to high pressures of heattransfer fluid, for example, high pressures of heating steam. This is incontrast to the construction of heated vessels known to the prior artwhere jackets rather than conduit wrappings are applied to vessel walls,and large panel areas of both jacket and vessel material are exposed tofluid pressures. In this prior art construction, therefore, wallthicknesses of both the vessels and their jackets must be rather largewhere steam pressures or other fluid pressures of any significantmagnitude are to be sustained. Since it does not have large panel areasexposed to fluid pressure as in the case of prior art constructions ofthe jacketed type, employment of the heat transfer fluid conduitwrapping of the present invention allows for a reduction in thickness ofmetal parts exposed to heat transfer fluid at any particular pressurerelative to such jacketed type constructions, for example, and soresults in a substantial economy of construction with respect to theweight of metal required.

Another advantage of the present invention which derives directly fromthe one just described is that with vessel walls of reduced thickness,and correspondingly reduced heat capacity and resistance to heat flow,the time needed to effect a significant temperature change in thecontents of a vessel when switching from a heating to a cooling fluid inthesurrounding conduit is substantially reduced. Thus, better control ofreactions going on within the vessel is achieved.

Referring next to FIG. 8, it will be seen that a special annular collaror shell 44 has been applied around the neck of bottom outlet fitting 23of vessel 22. This collar is welded or otherwise fluid-tightly attachedaround the fitting neck on its, the collars, inner periphery, and itmakes a similar fluid-tight joint with heat transfer fluid conduitwrapping 28 or volute transition piece 30 thereof, around its outerperiphery. The conduit defined by wrapping 28 including volutetransition piece 30 instead of discharging through fitting 4-2, as shownin FIG. 1, has been provided with a series of drain ports 46 openinginto the space bounded by the lowermost turn of the wrapping, the neckof outlet fitting 23, and the inner surface of collar 44. Thus, steam orcondensate descending within wrapping segment 28 must come into contactwith the neck of the bottom outlet fitting of vessel 22 before it isfinally discharged through an outlet fitting 48 set in collar 44. Bythis arrangement the heating effect, or a cooling effect if such bedesired, available from fluid circulated through the conduits defined bywrapping segment 28 and volute transition piece 30 is carried all theway down to and around the bottom outlet fitting of vessel 22 to givethermal control of the vessels contents right down to their very pointof discharge from the vessel.

Referring next to FIG. 9, a perspective end view is given of a segmentof heat transfer fluid conduit wrapping 50 according to a preferredembodiment of this invention which may be considered as representativeof the transverse elemental configurations of wrapping segments 24, 26,and 28 hereinbefore illustrated and described, wrapping 50 being shownin FIG. 9 separated from a vessel wall. Segment 50 has a generallyrounded transverse central portion 52 which terminates in outwardlycurved flaring edge portions 54 and 56. The outward flare of these edgeportions is significant for purposes of the present invention. The edgeportions should not, however, be turned out absolutely flat or straightupon at least one third of the radius of curvature R 6 their attachmentto a vessel Wall, but should have tangent lines or planes at an angle aof between 10 and 25, with respect to a base plane extending betweenthem as illustrated in FIG. 9. It has been found that it is desirablethat there be an angle of between 10 and 25 between a base planeextending between the edges of the wrapping and a tangential plane alongthe line of contact between each edge portion of the wrapping and thesurface of the vessel to which the wrapping is attached to getappropriate springing action of adjacent turns of wrapping and to ensurethat edge portions 54 and 56 make only lines of contact with the vesselwall, rather than planar contact. It is believed that the angulation ofthe edge portions and the fact that only lines of contact are made withthe vessel wall mitigate against the concentration of stresses in theweld and permits the wrapping to carry more of the stresses, thewrapping expanding and contracting in a bellow-like fashion with changesof temperature and pressure. It has been found that the angle a ispreferably about 10 to 15.

For purposes of illustrating desirable proportions and not of applyingany limiting dimensions, segment 50 may be considered as having athickness of A; inch, a base width W between longitudinal edges ofbetween four and five inches and a height H from its base plane to thecrown of its central rounded section 52 of about one and a half inches.In such an embodiment, the inside radius R of the central round sectionof segment 50 may be about one and a half inches and the inside radii Rof its outwardly curved flaring edges about a half inch. As in thisillustrative embodiment, it has been found desirable that the radius ofcurvature R of the flared edge portions of the wrapping be about onethird of the radius of curvature R of the central portion and that thethickness of the material of the wrapping be This relative proportioningof radii R and R and of the thickness of the wrapping material has beenfound to be preferable from the viewpoint of obtaining appropriatespringing action and strength of the wrapping with changes intemperature. It has been found that a wrapping having a base width W,height H, and radii of curvature R and R as recited above and a materialthicknes of about 0.125 inch, will sustain an internal fluid pressure of3,000 pounds per square inch (p.s.i.) when attached to a three-eighthsinch thick vessel wall. If it be assumed that a safety factor of 5:1 isdesired, the illustrated embodiment of this invention can be used with aworking pressure of 600 p.s.i., which far exceeds the working pressureand safety factor possible with prior art wrappings having correspondingthicknesses of materials. It is believed that the fact that a highworking pressure can be achieved with the wrapping of this invention isdue at least in part to the configuration of the outwardly curvedflaring edge portions of the wrapping, and that the configurationdescribed herein mitigates stresses in the welds due to expansion andcontraction of the wrapping with changes in temperature and pressure bythe wrappings ability to expand and contract in a bellows-like fashion.

Other transverse configurations of wrapping segments, for example,triangular configurations, may be employed within the scope of thisinvention, but as hereinbefore stated the rounded configuration shown inFIG. 9 represents a preferred embodiment. Whatever embodiment is used,it is important in any case for purposes of this invention that thewrapping segments longitudinal edges be extended outwardly curved sothat when adjacent turns of wrapping are together for attachment to thewall of the vessel as by welding, the region for deposit of the weldmetal, that is, the small region left between edges of adjacent turns,will be far enough away from the central sections of the wrapping turnsthat there will be no tendency of the welding flame or are to bediverted toward the central sections. Thus, while being sufficientlyclose to each-other that a single deposit of weld material may be usedto simultaneously bond adjacent turns both to each other and to thevessel wall, the turns are preferably also sufliciently spaced apart toprevent diversion of the weld flame or are toward the central portion ofthe wrapping and also to forstall splattering or other depositing ofweld material onto the central portion. It has been found that wrappingturns that are not spaced apart cannot be readily or satisfactorilywelded.

Referring next to FIG. 10, wrapping segment 50 is shown applied to aportion of a vessel wall 58 prior to actual attachment to this wall bywelding. Wall portion 58 may be considered similar to the straight orvertical cylindrical section or portion of the wall of vessel, 22 inFIG. 1. In FIG. it will be seen that because of the outwardly curvedflare of the edges cfadjaccnt wrapping turns there is ample room forweld' deposit to anchor the turns to the surface of wall portion 58 andto each other'only along their edges without any weld material beingspattered or otherwise deposited onto the central rounded section 52 ofthe .wrapping turns.

Referring next to FIG. 11, the'mode of attachment adjacent turns ofsegment 50 to each other and to the surface ,ofwallportion 58 by meansof a single deposit of weld material-60 is shown clearly. It Willbenotedparticularly that; because of the aforedescribed preferable 10"15angulation of the edge portions of the wrapping turns these portions donot come down flat against thesurface of base wall 58 ,when the edgeportionsv are welded to the wall, but'insteadmake lines of contact withwall'58. They thus have at least some possibility lines of contactwith'the wall instead of planar contact,

' it has been found that'thepossibility of the weld cracking withrelatively high fluid pressures and the wrapping being separated fromthe wall is mitigated. It is believed that this maybe due to the factthat, with only a line.

of contact, there will not be any spacing between the 1 vessel wall andparallelly disposed edgeportions of thewrappingin which the pressure ofthe fluid could exert oppositely directed separating forces. ,It isbelieved that due to the aforedescribedangulation of the edge portionsReferred next to FIGS. 12 and 13, 62 designates the overall assembly ofanother vessel such as a chemical blending retort provided with heattransfer fluid conduit wrapping according to the present invention. Thevessel itself, shown fragmentari-ly, is designated 64, and ischaracterized by a drum-shaped bottom above which there is anessentially straight cylindrical section. Aflixed to the exteriorsurface of the cylindrical wall portion of vessel 64 are four heattransfer fluid conduit wrappings or Wrapping segments 66, 68, 70 and 72.Two more wrappings or wrapping segments 74 and 76 are affixed to theexterior surface of the vessels druam shaped bottom. The conduitsdefined by wrappings 66, 68, 70', 72, 74 and 76 have upper fluidconnection fittings 78, 80, 82, 84, 86 and 88 respectively and the lowerfluid connection fittings 90, 92, 94, 96, 98 and 100 respectively. Thereis a bottom outlet fitting 102 on the vessel itself.

It is to be noted particularly that the several heat transfer fluidconduit wrappings are interwrapped in pairs on successive zones of thevessel wall surface. Specifically, wrappings 66 and 68 are interwrappedon one zone; wrappings 70 and 72 are interwrapped on another zone, andwrapping-s 74 and 76 are interwrapped on still another zone. Whether theupper fluid connection fittings on the conduits defined by these severalwrappings are to be regarded as inlet fittings and the lower fittingsthereon as outlet fittings or vice versa or some of each as one and someof each as theother will depend upon the thermal treatment tobe given tothe contents of vessel 64 in the carrying out of any particular reactionor process.

For purposes of a simple example, it may be assumed that the contents ofvessel 64- are to be highly heated and then rapidly chilled. Theconduits defined by wrappings 66, 72 and. 74. are to carry steam andthose defined by wrappings 68, 70, and 76 are to carry a refrigerant.Upper fluid connection fittings 78, 80, 82, 84, 86 and 88 are -to beused as inlet fittings, and lower fluid connection fittings 90, 92, 94,96, 98 and 100 are to be used as outlet fittings. Initially, steam issupplied to the conduits shownin FIG." 11, any such force that may occuris at least in part directed into the spring-like wrapping rather thanconcentrated at the weld; The single deposit of weld material 60 may, itis understood, be generated in the aggregate in either one pass or aplurality of passes of a welding rod. Among the factors determining thenumber'of passes actually required willbe the size of welding rod and.the thickness of material of wrapping segment;

In the actual practice of the present invention, it has been" found thatthe edge-to-edge spacing of adjacent turns or runs of wrapping segment50 should be varied tion of such metals:

Vessel Wall Wrapping Material Thickness, in.

Spacing between Ad- Thickness jaceut Edges of Wrapping Turns, in.

$6 13 ga. (.092 in.) is an.-- 12 ga (.108 in.) its 1 "do M 11 ga. (.125in.) 54

defined by wrappings 66, 72 and 74, and those defined by wrappings 68,70 and 76 are left idle. After the required processing time at hightemperature has elapsed, the steam is shut off and essentiallysimultaneously a flow of refrigerant is started through the conduitsdefined by wrappings 68, 70 and 76. Thus the chilling treatmentis'capable of being started even before the residual steam andcondensate in the conduits defined by wrappings 66,

v 72 and 74 has been drained away.

It will be apparent to those skilled in the art that much morecomplicated thermal treatments of the; contents of vessel64 could bedevised on a selective zone basis which would be capable of beingcarried out rapidly and with precision of timing of various particularthermal effects because of the high degree of flexibility of fluid flowarrangements provided by the distribution of wrappings 66, 68, 70, 72,74 and 76 according to the present invention.

Referring next to FIG. 14, 104designates the overall assembly of anothervessel such as a chemical blending retort provided with heat transferfluid conduit wrapping accordingly to the present invention. The vesselitself, shown fragmentarily, is designated 106. Aifixed by welding tothe exterior surface of a cylindrical wall portion of the vessel is afirst heat transfer fluid conduit wrapping segment 108. Superimposedupon and aflixed by welding to wrapping segment 108 is a second heattransfer fluid conduit wrapping segment 110. The deposit of weldmaterial whereby wrapping segment 110 is aflixed to wrapping segment108runs substantially along the crown of the latter segment.

A first or inner heat transfer fluid conduit 112 is defined betweenwrapping segment 108 and the exterior surface of vessel 106. A second orouter heat transfer fluid conduit 114 is defined between wrappingsegments 110 and 108. Appropriate inlet and outlet fittings, not shown,are provided on and in wrapping segments 108 and 110 so that heattransfer fluids may be admitted into and discharged from the twoconduitsl Inner conduit 112 may, for example, be used for circulation ofa heating fluid while outer conduit 114 is reversed for circulation of acooling fluid.

Assuming that the contents of vessel 106 are to be initially heated andsubsequently cooled, a liquid heating fluid such as oil or a saltsolution is first circulated through inner conduit 112. During theheating cycle or period there is no circulation of any fluid throughouter conduit 114. At the end of the heating period, circulation of theheating medium is terminated but conduit 112 is not drained; that is, itis left full of stagnant fluid. Circulation of cooling fluid throughouter conduit 114 is then started. During the cooling cycle or periodthe stagnant fluid within inner conduit 112 as well as the material ofwrapping segment 108 and that of vessel 106 acts as a heat transfermedium. The advantage of the arrangement shown in FIG. 14 is that theentire outer surface of the vessel 106 in way of wrapping segment 108 isavailable as a heat transfer surface during both the heating period andthe cooling period without any loss of time between the end ofcirculation of one heat transfer fluid and the beginning of circulationof another.

Referring next to FIG. 15, 116 designates the overall assembly ofanother vessel such as a chemical blending retort provided with heattransfer fluid conduit wrapping according to the present invention. Thevessel itself, shown fragmentarily, is designated 118. Afiixed bywelding to the exterior surface of a cylindrical wall portion of thevessel is a first heat transfer fluid conduit wrapping segment 120.Superimposed upon and aflixed by welding to wrapping segment 120 is asecond heat transfer fluid conduit wrapping segment 122. Superimposedupon and aifixed by welding to wrapping segment 122 is a third heattransfer fluid conduit wrapping segment 124. The deposits of weldmaterial whereby wrapping segment 122 is aflixed to wrapping segment 120and wrapping segment 124 is aflixed to wrapping segment 122 runsubstantially along the crowns of wrapping segments 120 and 122respectively.

A first or inside heat transfer fluid conduit 126 is defined betweenwrapping segment 120 and the exterior surface of vessel 118. A second orintermediate heat transfer fluid conduit 128 is defined between wrappingsegments 122 and 120. A third or outside heat transfer fluid conduit 130is defined between wrapping segments 124 and 122. Appropriate inlet andoutlet fittings, not shown, are provided on and in wrapping segments120, 122 and 124 so that heat transfer fluids may be admitted into anddischarged from the three conduits. Outside conduit 130 may, forexample, be used for circulation of a warming fluid, while intermediateconduit 128 is used for circulation of a medium heating fluid, andinside conduit 126 is used for circulation of a high heating fluid.During circulation of fluid through conduit 130, conduits 128 and 126would both be filled with fluids, preferably liquid fluids, to act asheat transfer media, while during circulation of fluid through conduit128 there would be a heat transfer fluid filling conduit 126.

The heat transfer fluid conduit wrapping arrangement of FIG. is anextension of that of FIG. 14, and can, of course, itself be extended toprovide four or any greater number of superimposed heat transfer fluidconduits on a single vessel as may be desired. It will be apparent tothose skilled in the art that with a plurality of such conduitsavailable, a wide and highly flexible variety of thermal treatments maybe imposed upon the contents of the wrapped vessel.

Referring next to FIGS. 16, 17, 18 and 19, 132 designates the overallassembly of another vessel such as a chemical blending retort providedwith heat transfer fluid conduit wrapping according to the presentinvention. The vessel itself, shown fragmentarily, is designated 134,and is characterized by an essentially drum shaped bottom 10 above whichthere is an essentially straight cylindrical section. Aflixed to theinterior surface of the cylindrical section of vessel 134 is a heattransfer fluid conduit. wrapping or wrapping segment 136. Anotherwrapping segment 138 is aflixed to the interior surface of the vesselsdrum shaped bottom.

The conduit defined by wrapping segment 136 is partly closed at itsupper end by a specially shaped plate 140 which is welded all around atits edges to the interior wall surface of vessel 134 and the transverseperiphery of the wrapping segment. This conduit is fully closed at itslower end by a suitable welded plate, not shown, or by being flatteneddown and welded to the vessels interior wall surface. At its upper end,wrapping segment 136 is cut on a bias as shown particularly in FIG. 18,with the attendant effect of enlarging the surface area of plate 140 atleast somewhat over what it would be if the wrapping segment were cutoff square. This allows the plate to be characterized by a fairly largehole or access opening 142 to which a pipe conductor 144, which does notpenetrate the vessel wall, may be connectedfor the supplying of fluid toor the carrying of fluid away from the conduit defined by wrappingsegment 136. This conduit has a lower fluid connection fitting 146 whichpenetrates the wall of the cylindrical section of vessel 134.

The spirally shaped conduit defined by heat transfer fluid conduitwrapping segment 138 has upper and lower or outer and inner fluidconnection fittings 148 and 150 which penetrate the drum shaped bottomof vessel 134. The ends of the conduit defined by this wrapping segmentare fully closed by suitable means such as welded plate 152. There is abottom outlet fitting 154 on the vessel itself. It is to be noted in theembodiment of the pres ent invention shown in FIGS. 16 and 17 that withthe heat transfer fluid conduit wrapping segments 136 and 138 applied tothe interior surface of vessel 134 with consequent transfer of heat toor from the vessels contents through the wrapping segments in the firstinstance, a heat transfer surface areafor these contents is providedwhich is at least somewhat greater than the interior wall surface areaof the vessel itself because of the undulating contour of wrappingsegments 136 and 138 as installed.

Referring to FIGS. 20 and 21, 156 designates the overall assembly ofanother vessel such as a chemical blending retort provided with heattransfer fluid conduit wrapping according to the present invention. Thevessel itself, shown fragmentarily, is designated 15%, and ischaracterized by an essentially flat bottom above which there is anessentially rectangular section. Affixed to the interior surface of theupper, rectangular section of vessel 158 is a heat transfer fluidconduit wrapping or wrapping segment 160. Another wrapping segment 162is affixed to the interior surface of the vessels flat bottom. Each ofthese overall segments comprises a plurality of individual segmentsmitred to each other at their ends as well as being welded to each otherand to the interior surfaces of vessel 158 along their longitudinaledges.

The conduits defined by wrapping segments 160 and 162 are each closed atboth ends by appropriate welded plates. The conduit defined by wrappingsegment 160 has upper and lower fluid connection fittings 164 and 166which penetrate the wall of the upper, rectangular section of vessel158. The conduit defined by wrapping segment 162 has outer and innerfluid connection fittings 168 and 170 which penertate the flat bottom ofvessel 158. No bottom outlet fitting is provided on vessel v158 asshown, the contents of the vessel being removed, when desired, bysuitable suction or pumping lines. Similar to the case of the embodimentof the present invention shown in FIGS 16 and 17, the heat transfersurface area for the contents of assembled vessel 156 is somewhatgreater than the interior wall surface area of the basic vessel 158itself on account of the undulating contour of its internal heattransfer fluid conduit wrapping.

Referring finally to FIGS. 22 and 23, these figures illustrate anotherembodiment of this invention in which a return bend heat transfer fluidconduit wrapping 200 having a substantially U-shaped longitudinal axisis employed. The return bend wrapping 200-is characterized by across-section perpendicular to its longitudinal axis which is in theform of a trough with outwardly curved flaring edge portions 202 and arounded central portion 204. As is shown in FIG. 22, the adjacent edgeportions of the return bend wrapping are spaced apart and adapted to bebonded to each other and to a surface of a vessel,

such as vessel 206 of FIG. 23, by a single deposit of weld material inthe space between the edge portions. The radius of curvature R of theoutwardly curved flaring edge portions is preferably one third of theradius of curvature R of the rounded central portion of the wrapping,and the thickness 'of the material of the wrapping is preferably atleast one third of the radius of curvature R There is an'angle a ofbetween .and 25, but preferably about 10 to between a base plane 208extending between the edges of wrapping 200 and a tangential'plane alongthe line of contact of the edge portion 202 and the base plane 208, andas was described above with reference to FIGS. 9 and 11 and anotherembodiment of thisinvention, when they are welded to the wall of avessel edge portions 202 preferably make only lines of contact with thevessel wall, rather than planar contact. The angulation andproportioning of edge portions 202, and the fact that only lines-ofcontact are made with the vessel wall, permit the wrapping 200 to expandand contract freely and also mitigate against the concentration ofstresses at the weld. Further, since adjacent wrapping turns are closetogether with only a weld between them,.the fluid in the heat transferfluid conduit makes maximum contact with the surface of the vessel towhich it is attached. This facilitates the inducing of rapid changes oftemperature in the vessels contents as almost, the entire wrappedportion of the vessel wall is heated or cooled;

The return bend wrapping 200,has an inlet opening 210 atone of its endsand an outlet opening 212 at its other end, andvwhen the wrapping isattached to vessel 206, it is connected in a fluid-tight relationship asby 'welding to adjacent ends of adjacent parallel conduit portions 214,thereby providing a continuous fluid passage way through the adjacentparallel conduit portions 214 and thereturn bend wr-appings 200.

Referring nowmore specifically to FIG. 23, vessel 206, constituting partof an overall vessel assembly 207,'has a substantially rectangular uppersection 216, and a lower section 218 with a curved surface. On thesurface of the upper section" of vessel 206 are a series of parallelwrapinclined rather than horizontal.

Wrappings corresponding to the wrapping just .described with referenceto the upper section of the, vessel 206 also appear on other surfaces ofthe'vessel. It is to be noted that the wrappings maybe interconnected soasto form a single continuous passageway for fluid by connectingsuitable auxiliary conduits to the inlet and.

outlet fittings, or they may be interconnected to form an upper zone ofheating or cooling, and a lower zone which might be at a diflerenttemperature. It is also to be noted that adjacent edge portions of thevarious wrapping segments are spaced apart sufficiently to forestalldiversion of the welding flame or are toward the central portion of the:wrappings and also to avoid splattering or other depositing of weldmaterial onto the central section, but, at

' the'same time, adjacent edge portions of the, wrapping segments aresufficiently close together that a single deposit of weld material maybe used to simultaneously fasten adjacent turns or runs both to eachother and also to the vessel wall.

It is thus seen that by practicing this invention in the mannersdescribed it is possible to obtain a vessel having a heat transfer fluidconduit wrapping attached to a surface thereof, the Wrapping turnshaving adjacent continuous edge portions which are spaced apart from oneanother and each having a transverse cross-section which is in the formof a trough with outwardly curved flaring edge portions making lines ofcontact with the surface of the vessel, and in which the wrapping isfurther characterized in that adjacent edge portions of the wrappingturns may be simultaneously bonded to each other and to the surface ofthe vessel at said lines of contact by a single deposit of weld materialin the space between the edge portions.

Further, although not specifically illustrated as an embodiment of thepresent invention, it will be clear to those skilled in the art on thebasis of what has been shown and described that heat transfer fluidconduit wrapping of the kind within the contemplation of this inventioncould be applied to the exterior as well as to the interior surfaces ofa rectangular, flat bottomed vessel such as vessel 158. It will also beclear to those skilled in the art that the cross-section of vesselsabout or upon which heat transfer fluid conduit wrapping of the kindwithin the contemplation of this invention may be applied, eitherexteriorly or interiorly, is not limited to one which is round or onewhich is rectangular. It may also be any reasonable one other than around one or a rectangular one such as one which is, for example,elliptical, oval, octagonal, hexagonal, pentagonal, or triangular.

Protection by Letters Patent of the present invention in all its aspectsas the same are set forth in the appended claims is sought to thebroadest extent that the prior art allows.

What-is claimed is:

1. A heat transfer fluid conduit wrapping for vessels adapted forattachment to a surface of a vessel by welding, the transversecross-section of the wrapping being in the form of a trough havingarounded central portion and outwardly curved flaring edge portions, andthe radius of curvature of each of said edge portions being about onethird of the radius of curvature of said central portion.

2. A heat transfer fluid conduit wrapping for vessels according to claim1, the thickness of the material of said wrapping being at least onethird of the radius of curvature of each of its edge portions.

3. A heat transfer fluid conduit wrapping for vessels adapted forattachment to a surface of a vessel by welding, the transversecross-section of the wrapping being in the for-m'of a trough withoutwardly curved flaring edge portions, in which said wrapping isfurther characterized by there being an angle of between 10 and 25between a base plane extending between the edges of the wrapping and atangential plane along the line of contact between each said edgeportion and the surface of the vessel.

4. A heat transfer fluid conduit wrapping for vessels adapted forattachment to a surface of a vessel by welding, the transversecross-section of the wrapping being in the form of a trough withoutwardly curved flaring edge portions, in which said wrapping isfurther characterized by there being an angle of about 10 between a baseplane extending between the edges of the wrapping and tangential planealong the line of contact between each said edge portion and the surfaceof the vessel.

5. A heat transfer fluid conduit wrapping for vessels adapted forattachment to a surface, of a vessel by welding, this wrapping being inthe form of a spirally-wound trough characterized 'by (1) a generallyrounded transverse cross sectional configuration, 2) outwardly curvedflaring edge portions along its open side, (3) one end and another end,-

1 3 and (4) a transverse cross sectional area which enlargescontinuously from said one end to said other end, the open side of saidtrough facing in a direction generally normal to the plane of spiralconfiguration of said trough.

6. A heat transfer fluid conduit wrapping for vessels according to claim5 which has an arcuate length of about 270.

7. A vessel having a heat transfer fluid conduit wrapping welded to asurface thereof, which wrapping has adjacent continuous conduit portionswhich are spaced apart from one another, each such conduit portion beingcharacterized by a transverse cross-section which is in the form of atrough with outwardly curved flaring edge portions which make lines ofcontact with said surface of the vessel, said wrapping being furthercharacterized in that adjacent edge portions of said conduit portionsare bonded to each other and to said surface of the vessel at said linesof con-tact by a single deposit of weld material in the space betweensaid edge portions.

8. A vessel according to claim 7 in which said surface of said vessel isan exterior surface.

9. A vessel according to claim 7 in which said surface of said vessel isan interior surface.

10. A vessel according to claim 7 in which there is an angle of between10 and 25 between the inner surface of the heat transfer fluid conduitwrapping and the surface of the vessel to which said Wrapping is bondedat their lines of contact.

11. A vessel according to claim 7 in which there is an angle of about 10between the inner surf-ace of the heat transfer fluid conduit wrappingand the surface of the vessel to which said wrapping is bonded at theirlines of contact.

12. A vessel according to claim 7 in which said wrapping is helicallybonded to said surface of the vessel by a single helical deposit of weldmaterial in the space between adjacent flaring edge portions of thewrappings.

13. A vessel according to claim 7 in which each conduit portion furthercomprises a rounded central portion and the radius of curvature of eachof said outwardly curved flaring edge portions is about one third of theradius of curvature of said central portion.

14. A vessel according to claim 7 in which the thickness of the materialof the wrapping is at least one third of the radius of curvature of eachof said outwardly curved flaring edge portions.

15. A vessel having a first heat transfer fluid conduit wrapping asrecited in claim 7 and a second heat transfer fluid conduit wrapping inthe form of a trough having outwardly curved flaring edge portions, saidsecond wrapping being bonded to the crown of said first wrapping by asingle deposit of weld material in the space between adjacent flaringedge portions of said second wrapping which bonds said adjacent edgeportions to each other and to the portion of the crown of said firstwrapping between them.

16. A vessel according to claim 7 in which the vessel has an end surfacewhich is substantially hemispherical and a first access opening fittingwhich extends through said end surface, the heat transfer fluid conduitwrapping being welded to said end surface and enclosing said fitting ina non-contacting relation; a collar making fluid-tight joints with saidfitting and said wrapping to define a chamber between itself, saidfitting, said wrapping and a portion of the surface of said vesseladjacent said fitting; and a second access opening fitting extendingfrom said chamber through said collar, said wrapping having at least onelateral opening in the wall thereof which forms a boundary of saidchamber to allow fluid to flow from the conduit defined within saidwrapping into said chamber.

17. A vessel having a plurality of heat transfer fluid conduit wrappingswelded to a side surface thereof in heat transfer relation withsuccessive zones of said side surface of the vessel, each of saidwrappings having independent inlet and outlet means, and each of saidwrappings having adjacent continuous conduit portions which are spacedapart from one another, each such conduit portion being characterized bya transverse cross-section Which is in the form of a trough withoutwardly curved flaring edge portions which make lines of contact withsaid side surface of the vessel, each of such wrappings being furthercharacterized in that adjacent edge portions of each of said conduitportions are bonded to each other and to said side surface of the vesselat said lines of contact by a single deposit of weld material in thespace between said edge portions.

18. A vessel having at least twoheat transfer fluid conduits defined ona surface thereof by first and second wrappings attached to said surfaceby welding, said wrappings each being in the form of a continuous troughcharacterized by outwardly curved flaring edge portions which make linesof contact with said surface, said first and second wrappings beinginterwrapped so that edges of said first wrapping lie adjacent butspaced apart from those of said second wrapping, and successive turns ofsaid wrappings about said vessel being so close that their adjacentedges are bonded to each other and to said surface of the vessel at saidlines of contact by a single deposit of weld material in the spacebetween said adjacent edges.

19. A vessel having a rounded end surface and further having a heattransfer fluid conduit defined on this surface by a wrapping attachedthereto by welding, said wrapping being in the form of a continuouslycurving, spirally-wound trough characterized by outwardly curved flaringedge portions along its open side whereagainst it is attached to saidsurface, said edge portions making lines of contact with said surface,and successive turns of said wrapping being in such spaced relation thattheir adjacent edges are attached to said end surface and to each otherby a single deposit of weld material in the space between said edgeportions.

20. A vessel according to claim 19 in which said end surface issubstantially hemispherical.

21. A vessel having a flat end surface and further having a heattransfer fluid conduit defined on this surface by a wrapping attachedthereto by welding, said wrapping being in the form of a continuous,spirally-wound trough characterized by (1) outwardly curved flaring edgeportions along its open side whereagainst it is attached to saidsurface, said edge portions making lines of contact with said surface,and (2) rectangular configuration having mitred corners on successiveturns, successive turns of said wrapping being in such spaced relationthat their adjacent edges are attached to said end surface and to eachother by a single deposit of weld material in the space between saidedge portions.

22. The combination comprising (1) a vessel having a rounded endsurface, (2) a first access opening fitting extending from the vesselthrough this surface, (3) a spirally-Wound wrapping attached to thissurface by welding to define a heat transfer fluid conduit thereon andenclosing said fitting in non-contacting relation, (4) a collar makingfluid-tight joints with said first access opening fitting and saidwrapping to define a chamber between itself, said fitting, saidWrapping, and a portion of the rounded end surface of said vesseladjacent said fitting, and (5) a second access opening fitting extendingfrom said chamber through said collar, said wrapping being characterizedby at least one lateral opening in its wall forming a boundary of saidchamber to allow fluid to flow from said conduit into said chamber.

23. The combination according to claim 22 in which said rounded endsurface is a bottom surface and said first access opening fitting is anoutlet fitting.

24. A vessel having a heat transfer fluid conduit wrapping welded to asurface thereof, which wrapping has (1) a plurality of substantiallyparallel conduit portions which are spaced apart from one another, eachsuch parallel conduit portion being characterized by a transversecross-section which is in the form of a trough with outwardly curvedflaring edge portions which make lines of contact with said surface ofthe vessel, said parallel conduit portions being further characterizedin that adjacent edge portions of said Wrapping are bonded to each otherand to said surface of the vessel at said lines of contact by a singledepositof weld material in the space between said edge portions; and (2)a return bend portion connected to adjacent ends of adjacent parallelconduit portions in a fluid-tight relationship therewith for providing acontinuous conduit path through said wrapping.

25. A vessel according to .claim 24 wherein the longitudinal axis ofsaidreturn bend portion is substantially U-shaped and wherein saidreturn bend portion is further characterized by (1). one end having aninlet opening thereat; (2) another end having .an outlet openingthereat, said one end being connected to an end of one of said parallelconduit portions in a fluid-tight relationship therewith and said otherend being connected to an adjacent end of an adjacent parallel conduitportion in a fluid-tight relationship therewith; (3) a cross-sectionperpendicular to said longitudinal axis which is in the form of a troughwith outwardly curved flaring edge portions which make lines of contactwith said surface of the vessel; and (4) adjacent, spaced apart edgeportions, the same being part of said outwardly curved flaring edgeportions, which are bonded'to each other and to said surface of thevessel at said lines of contact by a single deposit of weld material inthe space between said spaced apart edge portions.

26. A return bend heat'transfer fluid conduit wrapping for vesselsadapted for attachment to a surface of a vessel by welding,- wherein thelongitudinal axis of said return bend wrapping is substantially U-shapedand whereinsaid return'bend wrapping is further characterized by across-section perpendicular to said longitudinal axis which is in theform of a troughwith outwardly curved flaring edge portions, and whereinadjacent edge portions of said return bend wrapping are spaced apart andadapted to, be bonded to each other and to a surface of a vessel by asingle deposit of weld material in the space between said adjacent edgeportions.

27. A return bend heat transfer fluid conduit wrapping according toclaim 26 wherein said cross-section is further characterized by arounded central portion and wherein in said cross-section the radius ofcurvature of each of said outwardly curved flaring edge portions isabout one third of the radius of curvature of said central portion.

28.A return bend heat transfer fluid conduit wrapping according to claim27 wherein there is an angle of between 10 and 25 between a base planeextending between the edges of said return bend wrapping and atangential plane along the line of contact between each said edgeportion and the surface of the vessel.

29. A return bend heat transfer fluid conduit wrapping according toclaim 26 wherein there is an angle of about 10 between a base planeextending between the edges of said return bend wrapping and atangential plane along the line of contact between each said edgeportion and the surface of the vessel.

30. A return bend heat transfer fluid conduit wrapping according toclaim 26 wherein the thickness of the material of the wrapping is atleast one third of the radius of curvature of each of said outwardlycurved flaring edge portions.

References Cited by the Examiner UNITED STATES PATENTS 969,018 8/1910Willmann 165-109 1,657,202 1/1928 Ellyson 165147 2,671,658 3/1954 Moore165-147 X 2,772,860 12/1956 Nelson 165169 X 2,932,091 4/1960 Day 16516 9X 3,228,466 1/1966 Carleton 165-169 FOREIGN PATENTS 1,060,659 11/ 1953France.

43 2,970 8/ 1926 Germany.

646,866 6 1937 Germany.

804,008 4/ 1951 Germany.

ROBERT A. OLEARY, Primary Examiner.

MEYER PERLIN, Examiner.

A. W. DAVIS, Assistant Examiner.

1. A HEAT TRANSFER FLUID CONDUIT WRAPPING FOR VESSELS ADAPTED FORATTACHMENT TO A SURFACE OF A VESSEL BY WELDING, THE TRANSVERSECROSS-SECTION OF THE WRAPPING BEING IN THE FORM OF A TROUGH HAVING AROUNDED CENTRAL PORTION AND OUTWARDLY CURVED FLARING EDGE PORTIONS, ANDTHE RADIUS OF CURVATURE OF EACH OF SAID EDGE PORTIONS BEING ABOUT ONETHIRD OF THE RADIUS OF CURVATURE OF SAID CENRAL PORTION.